Automatic control means for stokers



Feb. 5, 1952 J. s. SKELLY AUTOMATIC CONTROL MEANS FOR STOKERS 4Shecs-Sheet 1 Filed April 50, 1948 i w F INVENTOR John S Skelly flafinai ATTORNEY Feb. 5, 1952 J. s. SKELLY 2,584,235

AUTOMATIC CONTROL MEANS FOR STOKERS Filed April so, 1948 4 Sheets-Sheet2 INVENTOR John S. Skelly Feb. 5, 1952 J. s. SKELLY AUTOMATIC CONTROLMEANS FOR STOKERS 4 Sheets-Sheet 5 Filed April 50, 1948 Stoker DriveMotor Speed Adjuster INVENTOR John S Skelly BY ATTOR Y Patented Feb. 5,1952 UNITED STATES orF AUTOMATIC CONTROL S FOR .STOKERS corporation ofDelaware Application Apri130, 8, Serial No. 24,13

'6 Claims.

My invention relates to the control of stokers which feed and burn coalor other fuel in furnaces utilized by steam generating boilers and/orother heating systems.

Broadly stated the object of my invention is to provide means forautomatically controlling the operating rate of such stokers includingunderfeed stokers equipped with an open-top retort having a screw-typefuel feeder and a reciprocating fuel pusher bar organized in the generalmanner disclosed by my U. 3. Patent 2,049,688 of August 4, 1936, forFuel Burning Device.

A more specific object is to provide improved means responsive tostoker-supplied heat demand for effecting an automatic control ofstokers such as are referred to above when same are equipped withvariable-speed-drive mech nisms organized as disclosed by my U. S.Patent 2,070,756 of February 15,1937, entitled Variable Speed Drive forMechanical stokers.

Another object is to overcome certain deficiencies in prior systems ofautomatic stoker control such as that disclosed by my 'U. 5. Patent2,199,012 of April 30, 1940, entitled Automatic Control Means forstokers.

A further object is to effect the foregoing automatic control of stokeroperating rate in such' an improved way as to avoid wastage of fuel,minimize smoke and increase fuel burning efficiency.

A still further object is to accomplish the desired control through themedium of apparatus which is low in cost, simple and compact inconstruction and reliable and trouble-free in operation.

Other objects and advantages of my invention will become apparent fromthe following description of illustrative embodiments thereof when readin conjunction with the accompanying drawings wherein:

Figure 1 is a view in longitudinal vertical sec tion of a stokerequipped with my improved automatic control and serving to fire a boilerwhich generates steam for heating and/or other purposes;

Figure 2 is a front elevational view (enlarged and looking from the'left in Figure 1) of the stokers operating and speed adjustingmechanism, some parts being shown in section on line 22 of Figure 3 toillustrate construction details;

Figure 3 is a side view, taken'on line 3-3 of Figure 2, of the stokerdriving mechanism showing my improvedspeed-selecting facilities appliedthereto;

Figure 4 is a diagram showing the electrical connections between thecontrol instrument (pressure-responsive here) and the speed-augustingmotor (on the stoKer) governed thereby pursuant to this invention;

Figure 5 is a front view of an instrument case in which the maincontrol, step-timer and selector devices utilized by my invention mayconveniently be housed;

Figures 6 and '1 are front and side views which correspond to Figs. 2and 3 and which disc ose another organization for the stokersspeed-selector actuating parts; and

Figure 8 is a diagrammatic showing of how the rearranged parts appearwhen viewed from line 8-8 of Fig. 6.

The drawings hereof show my automatic control improvements applied to anunderr'eed stoker whose organization is broadly similar to thatdisclosed and claimed by my earlier Patent 2,049,668 (of 1936) aboveidentified. This showing is merely illustrative and is not to beconsidered as restrictive; as the description proceeds it will becomeevident that my automate control improvements also are useful withadjustable-speed stokers of other designs.

The illustrative stoke) to be benefited In the stoker constructionillustrated, a wind 'box 9 organized as in my earlier Patent 2,049,668

of 1936 supports the stokers open-top retort it within the combustionchamber of a furnace 3. Coal or other fuel (not shown) is supplied tothe retort from hopper il outside the furnace by way of conveyor tube I2extending through the furnace front wall i3. Fuel conveyor screw i iwithin the tubeis rotated by motor l5 (or other power means) throughreduction gearing IS, the screw speed (relatively slow as several R.P.1M.) being selected by lever ll to provide the desired rate of fuelsupply. Entry of conveyor tube I2 into the retorts end wall i8 issomewhat above the retort bottom as shown.

Extending lengthwise of the retort I!) just above bottomwall is thestokers fuel feeder bar 22 which passes through front end wall is belowconveyor tube 12. As here shown, this feeder bar 22 rests on end bearingplates 23 and has the non-packi ng cross section taught by my U. S.Patent 2,433,713 of December 30, 1947, for Stoker Pusher Ba-r;reciprocating motion is imparted thereto by wobble cam 24 throughdriving bar 25 (which carries roller 2 and connecting plates 26; thebar-driving wobble cam 24 is-mounted in front of stoker hopper lloutside the furnace where it is rotated with conauxiliary pushers 36closer to the center of the main body of retort fuel) feeder bar 22,when reciprocated as aforesaid, progressively, advances fuel deliveredinto the retort by conveyor l4 away from the retorts front end wall andinto the main body of retort fuel (not here shown) toward inclining rearwall 3|. Such advancement displaces other fuel in that body upwardlytoward the burning fuel bed at the retorts opentop and outwardly upongrate bars 32-33 at the retorts top sides.

Air for supporting fuel combustion passes upwardly from Wind box 9 andthrough small passages 34 between fire bars 32-33. Such air may bemaintained under pressure in the wind box by a forced draft fan 36 (seeFigure 2) driven by motor i5 as taught by my earlier Patent 2,049,668 of1936. In proper cases a small portion of this wind box air may beadmitted over the bed of burning fuel through overfire passage 31 hereshown as including an adjusting damper 33.

All fire bars in the side rows 32-33 may be stationary, or certain barsin each row may be arranged to reciprocate toward and from the retort I0as taught by my U. S. Patent 2,136,807 of November 15, 1938, for SideRetort Stoker and as further disclosed by my Patent 2, 142,701 ofJanuary 3, 1939 for Underfeed Stoker. A dumping grate (not shown) alsomay be provided at the outer edge of each of these fire bar rows.

Stoker installation represented Underfeed stokers organized as heredisclosed in accordance with my earlier Patent 2,049,668 of 1936(application therefor filed in 1932) have enjoyed high commercialsuccess in such uses as firing the boilers of heating and power systemsfor schools, churches, apartment houses, garages and the like as well asin other applications including laundries, factories and otherindustrial establishments; this form of stoker uniquely combining theadvantages of the screw feed stoker and of the sliding bottom, pressureand plunger type of stoker without being subject to the disadvantagesinherent in those other stoker types;

In the illustrative application of Figure l the described stoker isshown as being mounted underneath a boiler 40 arranged to generate steamsupplied through outlet 4| to one or more utilizers typified by radiator42 employed to heat a room or other enclosure 43. The steam pressure insupply line 4| is indicated by a conventional gauge 4 3, while thetemperature of room 43 (heated by radiator 42) is responded to by athermostat 45.

The purpose of my invention is to provide improved means responsive tochanges in the reading of pressure gauge 44 or to the indication bythermostat 45 (or to some other measure of the demand forStoker-supplied heat) for automatically adjusting the stokersspeed-setting lever i! in a way which maintains the boiler-steampressure or the heated-room temperature (or other selected measure ofthe heat output by the controlled stoker) substantially constant.

The stokers drive and speed change mechanism The here representedvariable-speed stoker drive is broadly similar to that disclosed andclaimed by my earlier Patent 2,070,756 of 1937 previously identified.Stoker drive motor l5, stationarily mounted as shown, is of aconventional type suitable for energization from an elec- ,tricaipowercircuit of commercial voltage and frequency (such as 110 or 220 volts,25 or 60 cycles) and represented at A-BC in Figure l.

When so energized (as upon the closure of switch 4?) the motor rotatesat a substantially constant speed (of the order of 1700 to 1800 R. P.M.) sufficiently fast to operate forced-draft fan 36 (see Figure 2)efficiently.

A pulley 48 on the other end (right in Figure 2) of the motor shaftdrives belt is running over an intermediate pulley 50 mounted on a jackshaft 5| that is journaled in a bearing support 52 (see Figures 23)which is slidable along a track 53 that is pivoted at 56. Gravity andaspring 56 urge the free end of the track downwardly thereby keeping belt69 under proper tightness regardless of the position of slide sup port52 along track 53. In this Way pulley 50 rotates jack shaft 5| at asubstantially constant speed fixedly related to that of motor I5.

Driving into reduction gearing 16 for the purpose of rotating feed screwl4 and wobble cam 24 (at the relatively slow speed earlier indicated) isa third pulley 58 over which there rides a second belt 59 having theflat cross section shown. This second belt is driven from a compositepulley that is carried by the jack shaft 5% (see Figure 2) and thatincludes left and right members 565 and 6013 having opposedfrusto-conical faces against which the edges of belt 59 bear. Member 60Ais fixed to motor-driven pulley 56 on the jack shaftfwhile member 6033also receives turning movement from that shaft 5i but is slideablelengthwise thereof, it being urged toward 60A by spring 5| (again seeFigure 2).

Upon separation of members 60A and 66B, produced by a pulling of fiatbelt 59 closer to the center of pulley 60, the effective diameter ofthat composite pulley is reduced with the result that the gear box inputwheel 58 is driven at a lower rate of speed; likewise, upon closerapproach of members 60A and 6613 one to the other, as accompanies ariding (aided by spring 6%) of belt 59 farther from the pulley center,the eifective diameter of pulley 60 is increased with the result thatthe gear box input wheel 58 then is driven at a higher rate of speed. Tofacilitate the separation of members 60A and 603 when the belt 59 isplaced under added tension, the latter may satisfactorily be providedwith bevelled edges giving it the wedge shape represented.

.Belt 59 being of constant total length, the aforesaid effectivediameter of composite pulley 60 is determined by the position of jackshaft support 52 along slide 53. Serving to establish that position isthe earlier mentioned speed change lever l1 keyed as shown in Figure 2to the left end of an adjuster shaft 62 whose right end carries an arm63 as shown in Figures 23. A link 64 connects the lower end of arm 63with the slidable jack shaft support 52. With this arrangement movementof lever ll away from hopper II (to the left in Figures 1 and 3)increases the effective diameter of composite pulley 60 and hence raisesthe speed of gear box drive;

wheel 58; while movement of lever l1 toward hopper H (to the right inFigures 1 and 3) decreases the effective diameter of pulley B9 andcorrespondingly lowers the speed of gear box drive pulley 68.

Conventional reduction gearing within box it steps down the speed ofinput pulley 53 (of the order of several hundred of R. P. M. andadjustable as aforesaid) to a relatively low value (of the order of onlyseveral R. P. M.) suitable for rotating the stokers feed screw i i andwobble cam 25. Theseso driven feeder parts accordingly operate; (a) attheir minimum speed when lever ll is in the position closest in hopperII; (b) at a progressively increasing speed as lever ll is moved back(to the left in Figures 1 and 3) away from hopper l l; and (c) at theirmaximum speed when lever l1 occupies the position most remote from thehopper.

The gear box here illustrated is further provided with a clutch '86 bymeans of which the drive connection from motor E5 to the stokers fuelfeeder members l4 and 2d may at proper times be broken (as uponactuation of a suitable hand lever not represented). Such declutchingcompletely stops the stolrers fuel feed thereby allowing forced draftfan 36 to continue in operation, as is sometimes useful when it isdesired to burn v all the fuel in retort l9 and on grate bars 32-413before adding new fuel thereto. c The complete stoker of Figures l--2-3sti further includes for fan 36 an air intake fitting 6'! (see Figure 2)provided with conventional damper means (not here represented)controlled by a lever 68 and otherwise organized as disclosed by myearlier Patent 2,199,012 of 1940 as previously identified. Upwardmovement of this lever opens the inlet and thereby allows constant-speedfan 36 to supply (by way of air duct 69) more air to the stokers burningfuel bed; downward movement of this lever cuts down the area of inletopening and correspondingly reduces the supply of air to the fuel bed.

' Through suitable linkage means including shaft H (see Figure 2) andassociated elements l2--'i3'4, the position of damper lever 68 is madeto follow the position of fuel-feed speed selector lever H in such a waythat each increase in fuel feed rate is accompanied by a correspondingincrease in fan-air output, and vice versa; all as taught by my earlierPatent 2199,012 just mentioned. In this way the represented stokersimultaneously adjusts both its fuel-feed rate and its air-supply ratein a way assuring rnost effective fuel combustion throughout the entirerange of stoker operating speed.

Means for actuating speed selector lever 17 For imparting the requiredspeed-adjusting movements to lever ll my new control system utilizes areversing motor '56 which through reduction gearing ll drives a pinionit that meshes with a large gear wheel '19 mounted on idler shaft 80 andcarrying aroller 8i engaged by the forked opening '(see Figure 4) in "alever 82 attached at its lower end to the same sp eed-adj-uster shaft 62 as isupportsthe' stokers speed selector lever ll earlier described.

Control motor 76, shown as1mounted on top of the stokers main-drive gearbox H3, may satisfactorily be of fractional horse power capacitysuitable for energization from the alternating current voltage (110 or220 volts, 25 or 60 cycles) appearing between .two of the conductors ABCof the main power circuit which suppliesv stoker driving motor id asindicated in Figure 4. There current for operating control motor "1% isfed through conductors A and B. Connection (as later described) ofconductor A with motor terminal I produces forward rotation, whileconnection of A (again as later described) with terminal D causes motor'16 to rotate in the reverse direction.

The normally high speed (such as of theyorderof 1706-1800 R. P. M.) of.the control motor it is by gearing H (which may include a worm or otherequivalent drive) stepped down to the point where pinion it is driven atthe reiativeiy slow speed of onl two or three R. P. M. In consequencegear wheel 19 meshed with that pinion is during motor operation moved atan even slower rotational speed, so that forked lever 82 engaged bygear-carried roller 8! (see Figure l) requires a substantial time tomove from the extreme left position of Figure 4 (corresponding to theminimum stoker-speed setting of selector shaft 62) to the extreme rightposition of Figure 4 (corresponding to the maximum speed setting ofshaft 62).

In order to prevent motor 76 from moving forked lever 82 too farineither the speed-raising (right in Figure 4) or the speed-lowering(left in Figure 4) direction, use is made'of normallyclosed limitswitches 8d and 85 respectively inserted in the increase and in thedecrease I supply leads to motor 16, as per the diagram of Figure 4.These limit switches are conventional and lend themselves to mounting ina number of well known ways; one of these is indicated in Figures 2 and3 where the box representations tie-85 designate the two so numberedswitches of Figure land where the actuating means therefor take the formof a pin 88 protruding as shown from the bolt which secures roller illto the gear wheel 19. Still other arrangements may of course be employedto cause these limitswitches 8 l85 to selectively open when forked lever82 approaches the extremes in its range of adjustment positioning.

motor 7 6 In the illustrative organization shown by Figure 4energization of reversing speed-adjuster motor 76 is automaticallycontrolled by means of a novelly-organized system made up of: (1) apressure-responsive device '81 including a bellows 88 connected at 39;(see Figure 1) with the steam oiftake line it from boiler 43 andfunctioning to urge floating contact 90 against static-nary contact 'Hwhen the boiler pressure rises above a predetermined value and to engagefloating contact 90 with stationary contact L when the boiler pressuredrops below that value; (2) a step-timer device 92 including contacts93-434 which are repeatedly closed and opened under the cyclic action of.a cam 95 continuously rotated (at some relatively slow speed such asabout 1 R. P. M.) by a minimum; automatic; maximum) marked for purposeslater to be made evident; and (4) the interconnecting conductorsrepresented by Figure 4.

All three of the devices 81, 92 and 98 may satisfactorily be housed inan instrument casing indicated at Inn in each of Figures 1 and 5.

This casing can be made relatively compact, one practical designtherefor having height, width and depth dimensions approximating eight,seven and four inches respectively.

In this illustrative instrument organization the pressure-responsivedevice 81 is totally housed inside the casing I00, pressure connectionthereto being established through top tubing 89. Calibration of thisdevice 81 is adjusted by turning a top screw I92 which adjusts thetension on a spring I93 that opposes (see Figure 4) the tendency ofbellows 88 to close contacts Bil-H upon rising pressure of the boilersteam (see Figure 1). For each setting of screw I02 there exists apressure at which floating contact 99 is disengaged from both contacts Hand L. As thepressure in bellows 88 falls below that predetermined valuespring I93 brings contacts 90 and L together; and as the bellowspressure rises above that predetermined value the added bellowsexpansion brings contacts 90 and H together.

In the illustrative step timer shown at 92 (Figure 4), clock motor 96 isduring the represented automatic positioning of selector switch 98continuously energized over a circuit extending from supply conductor Athrough switch segment 99, conductors IDS-I06, the winding of timermotor 96 and conductor I01 back to supply conductor B. Under thiscondition motor 96 rotates timer cam 95 at some slow and uniform speedsuch as one R. P. M.; the two cam lobes represented then serving to movetimer contact 9 up and down once each 30 seconds in regularly repeatedcycles. Each upward movement engages contact 94 with companion contact93 while each downward movement breaks that engagement.

For adjusting the ratio of on (engaged) to off (disengaged) periods inthese recurring timer contact cycles, provision is made for moving theupper contact 93 either closer to or further away from the lower contact9d. As here shown this provision takes the form of a second cam 91settable in different rotational positions by a timer adjusting dial I08protruding through the front of instrument casing I as indicated inFigure 5. When dial I98 is turned counterclock wise to the extreme left,each thirty second cycle of timer operation will include a five secondon period during which contacts 93-99 are engaged, and a twenty-fivesecond off period during which contacts 93-94 are disengaged.

Turning dial 108 clockwise increases the length of the timer on periodsand decreases the length of the timer off periods. If set to the extremeclockwise direction (marked Increase in Figure the timer contacts 93-94will be engaged for twenty-five seconds and disengaged for five secondsduring each thirty second cycle. In this way there is provided a simpleand effective adjustment in the relative lengths of timer on and ofiperiods throughout a relatively wide range.

The four-position selector switch represented at 98 in Figure 4 isarranged for setting by means of a knob H0 extending through the frontof instrument casing I00 as shown in Figure 5. With the knob in thevertical or "automatic position representedswitch segment 99 connectsconductor A with conductor I05; turning knob IIB clockwise to themaximum position causes segment 99 to transfer the connection ofconductor A to a conductor I I2; shifting of the knob How the automaticcontrol system of Figure 4 operates In considering operation of thecomplete control system of Figure 4 assume that step timer 52 isadjusted so that each recurring thirty-second cycle of closing andopening by contacts 93-94 includes a fifteen second on period (contactsengaged) and a 15-second oii period (contacts disengaged); thatpressurestat 87 is set to hold contact 99 between contacts H and L whenthe pressure in boiler is (see Figure 1) has a selected value of 60pounds per square inch (as indicated by gauge 94); and that selectorswitch 98 is in the automatic position with segment 99 vertical asindicated.

In order to maintain the steam pressure in boiler at this value of 60pounds per square inch the stoker of Figure 1 will need to operate atsome intermediate value of fuel-feed rate such as istypified by therepresented position of manual speed selector lever ll (Figures-1-2-3)and by the corresponding intermediate position of forked lever 82 whichis fixed to the same speed-adjuster shaft 62 as is the first lever I'i.Underthese conditions contact of pressurestat 8i floats between contactsH and L and keeps both of terminals D and I of speed-adjuster motor "atdisconnected (at pressurestat 8'!) from supply conductor A.

Upon a drop in the steam pressure in boiler 59 (as may result when thedemand for supplied steam increases) pressurestat contact 99 engagescontact L thereby completing for feed adjuster motor '59 a forwardenergizing circuit which extends from supply conductor A throughselector switch 98, conductor [05, step-timer contacts 93-94 (whenrecurrently closed), conductor I I3, contacts sir-L of pressurestat Bl,conductor lit, limit switch 84, terminal I of motor 19, and the motorsforward driving winding back to supply conductor 13'.

Thus energized motor 19 rotates forwardly causing pinion 8 to drive gearwheel 19 in a direction (clockwise as viewed in Figure 4) to increasethe rate at which stoker feed screw 14 and wobble cam 24 (see Figure l)are driven by motor l5 and further to open the air damper 67 for forceddraft fan 39. This increasing adjustment in the rate of stoker fuel feedand air supply (accomplished through gear wheel 19 and forked lever 82)proceeds in step fashion; the adjuster motor '55 running only whenstep-timer contacts 93-94 are closed (fifteen out of each thirty secondsfor the assumed setting of step timer 92) and stopping during theintervening off periods (also assumed to be fifteen seconds each) whenthe step timer contactsareopened.

In consequence of the increased supply of fuel and air by the stoker tofurnace sthe steam pressure in boiler ill again builds up. Upon close approach thereof to 60 pounds per square inch, pres surestat contact 50-separates from contact L and thereby disconnects adjuster motor 86 fromsupply conductor A. Further corrective action by motor 16 is nowdiscontinued.

In the event that the steam pressure'in boiler 46 rises above theassumed predetermined value of 60 pounds per square inch (as may resultwhen the demand for boil-er supplied steam suddenly drops) pressurestat81 engages contact Eli? with contact If and thereby completes foradjuster motor '55 a reverse circuit which extends from supply conductorA through-selector switch conductor H35; contacts 93'$4 of steptimertii,conductor H3, contacts Elli-H of pressurestat 8?, conductor H5, limitswitch 85, terminal D of motor l8, and the motors reverse drivingwinding back to supply conductor B.

Thus energized motor I6 rotates reversely causing pinion E8 to drivegear whee]. E9 in a direction (counterclockwise as viewed in Figure 4)to decrease the rate at which stoker feed screw l4 and wobble cam 25(see Figure l) are driven by motor I and toeifect a closing adjustmentin the air damper Ell for forced draft fanBE. This "dc-creasingadjustment in the rate of stoker fuel and air feed proceeds in the samestep fashion (due to timer 92) as was explained for the increasingadjustment by motor lfi.

In consequence of the. decreased supply oi fuel and air by the stoker tofurnace 3 the steam pressure in boiler ie again falls. Upon closeapproach thereof to the. assumed 60 pounds per square inch desiredvalue, pressurestat contact separates from contact 1-! and therebydisconnects adjuster motor 76 (terminalD) from supply conductor A.Further corrective action by motor E5 is thereupon discontinued.

To adapt the system for maintaining the boiler steam pressure constantat some value other than the 60 pounds per square inch above assumed, itis only necessary to reset the pressurestat 8'? for contactdisengagement at the other pressure se lected. As already indicated, thenecessary re setting is readily accomplished by simply turning thecalibrating screw N22; to increase the tension on spring Hi3 when it isdesired to maintain a higher pressure and to decrease the spring tensionwhen it is desired to maintain a lower pressure. p i

Heat requirement measurements other than boiler steam pressure may alsobe used as the.

control factor in my improved automatic system. For example, thepressurestat tlof Figure 4 may be directly replaced in the circuitsdisclosed by the thermostat 35 of Figure 1. In effecting suchreplacement the thermostat contacts L, 3!? and II will be connected withconductors I Hi, H3 and i 55 in the same manner as-are the pressurestatcontacts 'L, as and H of Figure 4. 010-. eration of thethermostat-controlled system will then be the same as that abovedescribed for the; pressurestat-controlled system of Figure 4;'subjectto the single difference that the temperature of room 33 (Figure 1) willthen be main- 1 i an? speed.

lie

system of Figure 4 to hold the temperature of that water constant assome desired value.

In either arrangement step timer 92 functions to eliminate hunting oroverrunning in the fuelfeed adjustment made through motor '46 in thestoker driving mechanism of Figures l-23. Such hunting is prevented byadjusting the length of the timer on (closed contact) steps to suit thefuel burning characteristics of the stoker. As has been seen each onportion of the timer cycle is during corrective action accompanied by arunning of adjuster motor 76 and each intervening off (open contact)interval produces a waiting period between motor operations.

Hence with the thirty second cycle timer illustrated at 92 the earlierassumed fifteen second on and fifteen second off periods were chosenmerely to facilitate description. In certain fuel burning systems suchequal on and off periods may proye most suitable; in other systems ashorter on and a longer off period may prove most satisfactory; and instill other systems a longer on and a shorter off period may resuit inthe best operation. As earlier indicated the optimum adjustment for eachinstallation is readily efiected through timer-adjuster dial I98.

The step-timer 92 obviously may be connected into the control system inmanners other than the illustrative one shown by Figure 4. For eX-ample, the timer contacts 9394 may if desired (but not here shown) bereconnected to that they serve recurrently to interrupt only one ofspeed adjuster motor ltis forward and reverse energizing circuits M land H5 (instead of both as Figure 4 illustratively shows).

Moreover, by proper reorganization (not here illustrated) of the systemit is possible to make energization of timer motor 96 dependent uponengagement of the contacts (-4-1 or 90-L) in master control device ill.With such an arrangement the timer cam 95 will be rotated only when thestokers speed-adjuster motor 96 is energized (at one or the other of itsterminals D and I); this permits inactivity on the part of timer device$32 at all times except when motor 16 actually is being called upon toadjust the stoker Non-automatic control of the stokers fuel-feed speedUnder certain conditions it may be desirable shaft or under manualcontrol independently of the automatic facilities just described.Provision for doing this is made in my new system. In the organizationshown by Figures 1 to 5 such provision includes the selector switch 98plus a releasable clutch mounting for pinion 18 which drives into gearwheel 79 (see Figure 4) from motor '56.

Referring to, Figure 2, pinion 18 is there shown as being looselymounted on the shaft I H of the control motor assemblage lii'lland-receives turning movement therefrom through a collar H3 fixed to theshaft. Abutting ends of tained constant instead of the steam pressure into this collar and gear "it are each provided with V boiler ill.Furthermore, temperature-responsive contacts such as H--%L" can also beincorporated into an aquastat (not shown) submerged in water heated bythe stokerefired furnace 8 and functioningthroughmynew control notchesH9 which look into each other as long as a hand screw me on shaft H'lsthreaded end holds gear '58 against collar I I8. Under these conditionspinion i8 is rigidly fixed to and rotates with the shaft 1 ll of speedadjuster motor ll gearing 11. The effect then is the same as were pinion18 to be keyed to shaft I I1.

Should, however, it be desired to utilize manual lever I1 for settingthe stokers fuel-feed speed, it is only necessary to turn hand screw I20along threaded shaft end II'I away from gear 18 for a short distance aslimited by cotter key I2I. The V notches I I9 now are effective todisengage gear 18 from collar II 8 and allow it to rotate freely onshaft I I1.

Pinion 18 is in this way freed to turn loosely on shaft II1. Under thiscondition forked lever 82 (see Figure 4) can under the turning action(through shaft 62) of hand lever I1 rotate gear wheel 19 (through roller9|) to any speedad justing position which it may be desired to establishby lever I1. Once the position is so selected, it may be there held byretightening hand screw I28 against pinion 18, thereby again looking itto control gearing shaft II1. Access to hand screw I22 may convenientlybe provided for by equipping the casing of the stoker drivemechanismwith an access door as shown at I22 in Figure 3. e

Incident to the foregoing manual setting of the stoker feed drive, theselector switch 98 of Figures 4 and 5 is preferably set to the offposition wherein supply conductor A is disconnected from all three ofsystem conductors H35, 7

III and H2.

Under certain conditions this selector switch 98 is further useful inselectivelv running the speed-adjuster motor 16 (with pinion 18 lockedto shaft III) to the extreme position for forked lever 82 in either themaximum or the minimum speed-adjusting direction.

Such maximum-direction running results when knob IIO of the switch isrotated clockwise to its maximum osition to connect (through segment 99)supply conductor A with system conductor II2. This by-passes both thestep-timer 92 and pressurestat 81 by connecting A directly to motorconductor I I I, thereby energizing motor terminal I and causing gearwheel 19 to be advanced in the speed-increasing direction (clockwise asviewed in Figure 4) until forked lever 82 contacts and opens limitswitch 84 in the motor circuit. Motor 16 then stops with forked lever 82in the maximum fuel-feed position.

To run motor 16 to the opposite or minimum range of travel for speedadjusting lever 82, it is only necessary to turn knob III! of selectorswitch 98 counterclockwise to the minimum position wherein segment 99connects supply conductor A with system conductor III. Devices 92 and 81are again bv-passed and the resultant connection of A with conductor II5applies energizing voltage to terminal D of motor 15. This causes themotor to rotate gear wheel 19 in the fuel-speed decreasing direction(counterclockwise in Figure 4) until forked lever 82 contacts and opensselector switch 85 to interrupt the supply circuit and stop the motorwith lever 82 in the position of minimum fuel-feed adjustment.

As earlier indicated a setting of selector switch 98 in the off positiondisconnects supply conductor A from all other system conductors andthereby renders speed adjuster motor 15 totally inactive.

The modified speed-adjusting mechanism of Figs. 6-7-8 Figures 6-7-8disclose an alternative organization for the parts through which gearwheel 19 (driven by control motor 16) transmits speed adjustingmovements to the shaft 62 of the stokers speed selector mechanismearlier described. In this alternative organization: (a) the two arms I1and 82 of Figures 2-3 are replaced by a single arm shown at I1 inFigures 6-7-8; (b) the pinion 18 for driving gear wheel 19 is fixedlymounted on the shaft II1 of the control motor assemblage 16-11; (0) gearwheel 19 has supported from its left face (as viewed in Figure 6) a discI24 upon which is mounted the roller 8I' that engages one side of arm I1as shown; (d) enough of the casing wall I21 is cut away opposite gearwheel 19 to permit the engagement named; and (e) movement of arm I? inthe speed raising direction can at proper times be limited to a selectedposition by placing a stop pin I26 ahead of the arm (on same side asroller 8I') in one of the holes provided in a bracket I28 that issecured to the stoker casing I29 as shown.

Except for the changes above listed, the speedchange mechanismrepresented in Figures 6-7- 8 duplicates that already described byreference to Figures 2-3. In it lever I1 is continuously urged against(to the left in Figure '7 and to the right in Figure 8) roller 8I' dueto the tendency of composite pulley B0 to ride belt 59 as far towardsthe outer edges of beveled members GOA-60B as the positions of link 64,arm I53 and speed-change shaft 62 will permit. The named tendencyresults from the continuous urging by pulley spring 6| (see Figure 6) ofmember 6013 towards member 60A; this, in turn, urges belt 59 away fromthe center of pulley 60; and, in consequence, the shaft support 62 forthat pulley continuously urges link 64 to the right in Figure 7. Arm 63converts that urge into a torque on shaft 62 which is counterclockwiseas viewed in Figure 7 and clockwise as viewed in Figure 8 and whichcontinuously urges lever I1 towards roller 8I as earlier stated.

This modified mechanism of Figures 6-7-8 employs the same reversingmotor 16 as does the mechanism of Figures 1-2-3 and it contem platesthat this motor 16 be automatically con trolled through the novelapparatus shown in Figure 4, as earlier described in detail. In 9.0--tual use the parts of Figure 8 therefore form part of the completeautomatic control system of Figure 4; lever I1 of Figure 8 thenreplacing the forked arm 82 of Figure 4 and limit switches'9e and 85then being actuated (at proper times) directly from the gear wheel 19through the actuator 86' carried thereby as indicated in each of Figures6-7-8.

Operation of the complete automatic control system so disclosed byFigures 4, 6-7-8 therefore proceeds in the same way as was earlierexplained for the equipment of Figures 1 through 5. In examining thisoperation first assume that stop pin I26 is removed from bracket I28thereby allowing lever I1' freely to follow roller 8i through all speedadjusting rotations of gear wheel 19. Under this condition the modifiedlinkage mechanism of Figures 6-7-8 functions in precisely the samemanner as does the mechanism of Figures 2-3-4, except that lever I1"takes the placeof forked arm 82.

Thus, rotation ofgear wheel 19. in the speed decreasing direction(counterclockwise in Figure 8 and clockwise in Figure 7) pushes lever I1to the right in Figure 7 (and to the left in Figure 8) thereby causinglink 64 to push composite pulley 50, further away (to left in Figure 7)from the fixedly mounted pulley 58 over which the belt 59 rides. Thispulls belt closer to the composite pulleys center and therebyappropriately reduces the stoker driving speed; such reduction beingaccompanied by a corresponding adjustment of air damper 53 (throughlinkage ll-44) in the draft reducing direction.

Similarly, rotation of gear wheel 7% in the,

speed increasing direction (clockwise in Figure 8 and counterclockwisein Figure 7) allows lever H to follow roller 8 l to the left in'Figure'7 (and to the right in Figure 8) and thereby permits composite pulley50 (urged by spring iii) to ride belt 59 closer to the pulleys outeredges with a resultant increase in stoker driving speed. moving, asstated, lever ll effects a corresponding adjustment of air damper $3 inthe draft increasing direction.

This modified apparatus of Figures 6--7--8 offers special advantages,The first of these is that of permitting ready establishment of an upperdriving speed limit at some selected value that is less than the highestattainable stoker speed which rotation of gear wheel '59 into itsextreme speed increasing position (wherein limit switch' 84 opens)determines. Such establishment of a reduced upper limit is accomplishedby inserting stop pin I26 into the opening along the length of bracketI28 which corresponds to the particular reduced upper limit desired.

Under this condition (represented in each of Figures 6-7-8), automaticstoker adjustments within the speed range below that selected by pin I26continue to proceed as before. However, once lever i1 is by roller 8!allowed to move into contact with pin 12% then further advancement ofthe lever is prevented even though gear wheel '59 may be further rotatedby control motor '15 in the speed'increasing direction. This means thatthe automatic control facilities are rendered ineffective within therange above the intermediate speed value selected by pin 126.

A second advantage afforded by the modified apparatus of Figures 67-8isthat of permitting a setting of the speed adjuster lever ll} underfull manual control and with complete independence of the automaticfacilities diagrammed in Figures 4 and 8. To accomplish Summary From theforegoing it will be seen that I have provided improved means forautomatically controlling the operating rate of stokers includingundcrfeed' stokers organized as taught by my Patent 2.9%,668 of 1936 andequipped with varispeed drive mechanisms as taught by my Patent2,070,756 of 1937; that I have effected the foregoing automatic controlof stoker operating rate in such an improvedway as to avoid wastage offuel, minimize smoke and increase fuel burning efficiency; that I haveaccomplished the desired control through the medium of equipment whichis low in cost, simple and compact in construction and reliable andtrouble-free in operation; and that I have organized the automaticcontrol apparatus in a way permitting the sicker operating speed to beadjusted manually, when and if desired.

My inventive improvements are therefore extensive in their applicationand hence are not to be restricted to the specific form here disclosedby way of illustration.

What I claim is:

1. In combination, a furnace, a stoker therefor including fuel-feedelements, continuously operthis it is only necessary to turn selectorswitch 53 of Figure 4 to the maximum position.

Such turning connects (through segment 99) supply conductor A withsystem conductor H2. This by-passes both the step timer 52 andpressures-tat 8i by connecting A directly to the motor conductor li ithereby energizing terminal I of .motor 16 and causing gear wheel E9 tobe advanced in the speed increasing direction (clockwise as viewed inFigure 8) until actuator 86 contacts and opens limit switch in theforward motor circuit. Motor it then stops with the roller 3! in themaximum full speed position (to the right in Figure 8 and to the left inFigure 7).

Roller Si is now completely out of the normal-range path of lever ii andthat lever is accordingly free for manual setting to any position in thestoker speed range which may be desired. Each such selected position cannow readily be retained by inserting stop pin 126 in the appropriateplace along the length of bracket 23. It will thus be seen that themodified organization of Figures 6-'?--3 permits manual setting of thestoker feed speed to be effected motor assemblage shaft ill.

able mechanism for driving said elements, a member in said mechanismmovable to adjust the speed at which said fuel-feed elements are driven,a gear wheel rotatively mounted to impart speed-adjusting movement tosaid member,

" an electric motor for slowly rotating said gear Wheel through ameshing pinion mounted on a motor-driven shaft, an instrument responsiveto the demand for furnace-supplied heat, first contacts engaged by saidinstrument when said supplied heat falls below said demand, secondcontacts engaged by said instrument when said supplied heat rises abovesaid demand, a forward energizing circuit for said motor completedduring each engagement of said first contacts and then effective tocause the motor to move said stoker-adjusting member in the fuel-feedincreasing direction, a reverse energizing circuit for said motorcompleted during each engagement of said second contacts and theneffective to cause the motor tomove said stoker-adjusting member in thefuel-feed decreasing direction, a

selector switch forat times rendering said forward and reverse motorcircuits both unresponsive to said automatic instrument control, andmeans mounting said gear-driving pinion on said motor-driven shaftv in away permitting selective release of the. shaft-to-pinion drivingconnection when during the aforesaid times it may be desired to freesaid gear wheel for a manual rotative shifting to any selected point insaid stoker-adiusting inembers range of feed-speed varying movement.

, 2. In combination, av furnace, a stoker for supplying said furnacewith fuel to be burned therewithin and with air to support said burning,continuously operable stoker driving mechanism including a levereffective to adjust therate at which the stoker feeds both said fuel andsaid air into the furnace, a gear wheel rotatively mounted to impartspeed-adjustingmovement to said lever, a pinion meshing with said gearwheel and carried by a shaft, an electric motor for driving said shaftin order slowly to rotate said gear wheel through said pinion, aninstrument responsive to the demand for furnace-supplied heat andeffective to engage a first set of contacts when said supplied heat isless than said demand and to engage a second set of contacts when saidsupplied heat is greater than said demand, a forward energizing circuitfor said motor completed during each engagement of said first contactsand then effective to cause the motor to move said stoker-adjustinglever in the fuel-feed-increasing direction, a reverse energizingcircuit for said motor completed during each engagement of said secondcontacts and then effective to cause the motor to move said lever in thefuel-feed-decreasing direction, a selector switch for at times renderingsaid forward and reverse motor circuits both unresponsive to saidautomatic instrument control, and means mounting said gear-drivingpinion on said motor-driven shaft in a way permitting selective releaseof the shaft-to-pinion driving connection when during the aforesaidtimes it may be desired to free said gear wheel for a manual rotativeshifting to any selected point in said stoker-adjusting levers range offeed-rate varying movement.

3. In combination, a furnace, a stoker for supplying said furnace withfuel to be burned therewithin and with air to support said burning,continuously operable stoker driving mechanism including a levereffective to adjust the rate at which the stoker feeds said fuel and airinto the furnace, said lever being settable anywhere between an extremelow speed position and an extreme high speed position, means urging saidlever in the direction of its said high speed position, a gear wheelrotatively mounted and carrying at a point displaced from its axis a-roller organized to restrain said lever from travel beyond the rollertowards said extreme high speed position, an electric motor forimparting rotation to said gear wheel, a motor-control instrumentresponsive to the demand for furnace-supplied heat, a forward energizingcircuit for said motor activated by said instrument when said suppliedheat is less than said demand and then effective to produce forwardrotation of said gear wheel causing said roller to allow advancement ofsaid lever in the feed-speed-increasing direction, a reverse energizingcircuit for said motor activated by said instrument when said suppliedheat is greaterthan said demand and then effective to producereverserotation of said gear wheel causing said roller to move said lever inthe feed-speed-decreasing direction, and means supplemental to saidmotor-driven gear wheel and roller for restricting said lever in itssaid speed-raising movement to a selected intermediate position in theaforesaid lever travel range notwithstanding that said gear wheel mayadvance said roller in the speed-raising direction to beyond saidselected intermediate position.

4. In combination, a furnace, a stoker for supplying said furnace withfuel to be burned therewithin and with air to support said burning,continuously operable stoker driving mechanism including a leverefiective to adjust the rate at which the stoker feeds said fuel and airinto the furnace, said lever being settable anywhere between an extremelow speed position and an extreme high speed position, means urging saidlever in the direction of its said extreme high speed position, a gearwheel rotatively mounted and carrying at a, point displaced from itsaxis a roller organized to restrain said lever from travel beyond theroller towards said extreme high speed position, an electric motor forimparting rotation to said gear wheel, a motorcontrol instrumentresponsive to the demand for furnace-supplied heat, a forward energizingcircuit for said motor activated by said instrument when said suppliedheat is less than said demand and then effective to produce forwardrotation of said gear wheel which causes said roller to allowadvancement of said lever in the feedspeed-increasing direction, areverse energizing circuit for said motor activated by said instru mentwhen said supplied heat is greater than said demand and then effectiveto produce reverse rotation of said gear wheel which causes said rollerto move said lever in the feed-speeddecreasing direction, meansincluding a selector switch for at times rendering said forward andreverse motor circuits both unresponsive to said automatic instrumentcontrol and for thereupon causing the motor to drive said gear wheelforwardly to a position wherein said roller frees said lever for fulladvancement into its said extreme high speed position, and meanseffective to hold said lever in any position within its complete rangeof travel that during the aforesaid times it may be desired to select bymanual setting.

5. In combination, a furnace, a stoker for supplying said furnace withfuel to be burned therewithin, continuously operable stoker drivingmechanism including a lever effective to adjust the rate at which thestoker feeds said fuel into the furnace, said lever being movablebetween an extreme low-speed position and an extreme high-speedposition, a gear wheel rotatively mounted and carrying a roller at apoint displaced from the gear wheel axis, means causing said leverto'move with said roller upon changes in the rotational position of saidgear wheel, an electric motor for imparting rotation to said gear wheel,a motor-control instrument responsive to the demand for furnace-suppliedheat, a forward energizing circuit for said motor activated by saidinstrument when said supplied heat is less than said demand and thenelfective to produce forward rotation of said gear wheel causing saidroller and said lever to move in the feed-speed-increasing direction, areverse energizing circuit for said motor activated by said instrumentwhen said supplied heat is greater than said demand and then effectiveto produce reverse rotation of said gear wheel causing said roller andsaid lever to move in the feed-speeddecreasing direction, and a selectorswitch for at times rendering said forward and reverse motor circuitsboth unresponsive to said automatic instrument control and for at othertimes enabling each circuit selectively to be supplied with energizingcurrent under manual control directly through the switch in by passrelation to said instrument.

6. In combination, a furnace, a stoker for supplying said furnace withfuel to be burned therewithin, continuously operable stoker drivingmechanism including a lever effective to adjust the rate at which saidstoker feeds fuel into the furnace, said lever being movable between anextreme low-speed position and an extreme highspeed position, a gearwheel rotatively mounted and carrying a roller at a point displaced fromthe gear wheel axis, means causing said lever to move with said rollerupon changes in the" rotational position of said gear wheel, an electricmotor for imparting rotation to said gear wheel, a motor-controlinstrument responsive to the demand for furnace-supplied heat, a forwardenergizing circuit for said motor activated by said instrument when saidsupplied heat is less than said demand and then effective to produceforward rotation of said gear wheel causing said roller and said leverto move in the feed-speedincreasing direction, a reverse energizingcircuit for said motor activated by said instrument when said suppliedheat is greater than said demand and then effective to produce reverserotation 01. said gear wheel causing said roller and said lever to movein the ieed-speed-decreasing directicn, a timing device for said forwardand reverse motor circuits effective upon activation of each asaforesaid then recurrentiy to interrupt the activated circuit andthereby cause said steker-speed-adjusting motor to operate in recurringsteps which are separated by intervening periods or" motor stoppage, aselector switch for at times rendering said forward and reverse motorcircuits both unresponsive to the foregoing automatic instrument controland for at other times enabling each circuit selectively to be suppliedwith energizing current under manual control. directly through theswitch in by pass relation to said instrument and said timing device, afirst limit switch functioning to deactivate said forward motor circuitupon either instru ment or selector-switch initiated movement by saidmotor of said stoker-adjusting lever to its extreme limit of travel inthe fuel-feed-increasing direction, and a second limit switchfunctioning to deactivate said reverse motor circuit upon eitherinstrument or selector-switch initiated movement by said motor of saidstoker-ad- ,iusting lever to its extreme limit of travel in thefuel-feed-decreasing direction.

JOHN S. SKELLY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,335,008 Miner Mar. 30, 19201,418,871 Harrington June 6, 1922 1,472,280 Ousdahl Oct. 30, 19231,520,922 Baker Dec. 30, 1924 1,698,989 Chadwick et a1. Jan. 15, 19292,012,934 Hardgrove Aug. 27, 1935 2,070,756 Skelly Feb. 16, 19372,196,802 Potter et al. Apr. 9, 1940 2,251,483 Denison et al. Aug. 5,1941 FOREIGN PATENTS Number Country Date 332,440 Germany Feb. 5, 1921OTHER REFERENCES Ser. No. 421,940, Kool, et al. (A. P. 0.), publishedMay 25, 1943.

